Knotless suture anchor

ABSTRACT

A suture anchor is disclosed having an outer body with an axial bore which receives and inner body for rotation. Suture passes between the inner body and outer body and rotation of the inner body wraps the suture thereabout locking the suture thereto. Rotation of the inner body also effects radial expansion of at least a portion of the outer body to engage to anchor into a bone hole.

BACKGROUND

The present application relates to suture anchors and more particularlyto a knotless suture anchor.

Suture anchors have wide use in surgery particularly for reattachingsoft tissue to bone. It is preferred to perform most of these surgeriesendoscopically. While working through a long narrow endoscope knot tyingtakes on added difficulty. Accordingly it is frequently preferred toemploy a suture anchor which can capture the suture without the need ofthe surgeon having to tie a knot. It is also preferred that whilecapturing the suture to lock it to the anchor that the anchor notdisturb the tension on the suture. Typically the soft tissue iscarefully positioned just prior to locking the suture and if the act oflocking the suture causes it to move it can affect the position of thesoft tissue.

SUMMARY OF THE INVENTION

A suture anchor according to the present invention comprises an outerbody having a distal end a proximal end and an axial bore therethrough.An inner body is receivable within the outer body. A suture limb iscaptured between the inner body and the outer body by being wrappedaround the inner body.

Preferably, the inner body and the outer body are formed of abioabsorbable material, as for example a material comprising PLGA.

Preferably, the inner body and outer body are threaded together.

Preferably, the suture anchor is configured such that as the inner bodyis moved toward the proximal end of the outer body the proximal end ofthe outer body expands outwardly radially.

Preferably, the suture limb is wrapped around the inner body at leasttwo times. Enhanced holding is provided when the suture limb is wrappedaround the inner body at least five times.

Preferably, the inner body comprises at least one tab extendingoutwardly radially whereby to effect wrapping of the suture about theinner body upon rotation of the inner body.

Preferably, the inner body has a distal end and a proximal end andwherein the inner body proximal has outer threads which mate with innerthreads on the proximal end of the outer body. Preferably, an inserteris provided having a distal end which mates with the proximal end of theinner body and which has outer inserter threads engageable with theinner threads on the outer body. Preferably, the outer body has a firstconfiguration in which at least a portion thereof is radially contractedinwardly and a second configuration in which the portion is radiallyexpanded outwardly, and wherein when the outer inserter threads areengaged into the outer body inner threads it holds the portion in thesecond configuration. Similarly, when the outer threads on the innerbody are engaged into the outer body inner threads it holds the portionin the second configuration. Preferably, a naturally relaxed position ofthe portion is in the second configuration. Thus, when the outer body isexpanded into the bone internal stresses on the outer body areminimized.

In one aspect of the invention, the suture limb passes into a spaceformed between the inner body and the outer body at their proximal ends,passes out of the space at their distal ends and then passes proximallyalong an outer surface of the outer body.

Preferably, the outer body has at its proximal end at least one axiallyextending slit therein whereby to relieve stresses upon radially outwardexpansion of the outer body proximal end.

In one aspect of the invention, at least one more suture limb iscaptured between the inner body and the outer body or perhaps at leastthree more suture limbs captured between the inner body and the outerbody.

A method according to the present invention provides for attachingtissue to a bone. It comprises the steps of: passing a limb of suturefrom the tissue between a suture anchor outer body, which has a distalend a proximal end and an axial bore therethrough, and an inner bodyreceivable within the outer body; inserting the outer body into thebone; sliding the suture between the inner body and the outer body toachieve a desired tension thereon or desired position of the tissue;capturing the suture limb between the inner body and the outer body, bywrapping at least a segment of the suture limb about the inner body, toprevent sliding of the suture limb therebetween.

Preferably, the distance between the tissue and the anchor stayssubstantially the same during the step of capturing.

Preferably, the suture limb is wrapped around the inner body at leasttwo times.

Preferably, the inner body has at least one radially extendingprojection and the step of wrapping comprises rotating the inner bodywithin the outer body during which the projection engages the suturelimb to cause it to wrap about the inner body.

Preferably, the method further comprises the step of radially expandingat least a portion of the outer body to engage the suture anchor intothe bone. For instance when a proximal end of the inner body has outerthreads and the proximal end of the outer body has mating inner threadsthen the step of radially expanding can comprise engaging the inner bodyouter threads with the outer body inner threads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cut-away view of a suture anchor according tothe present invention;

FIG. 2 is a perspective view of the suture anchor of FIG. 1;

FIG. 3 is a perspective view of the suture anchor of FIG. 1 pre-loadedwith a suture capture device;

FIG. 4 is a side elevation view in cut-away of soft tissue andassociated bone showing initial insertion of the suture anchor of FIG.1;

FIG. 5. is a side elevation view in cut away of the soft tissue and boneof FIG. 4 showing free ends of a suture between the soft tissue and theanchor being pulled to tension the suture and position the soft tissue;

FIG. 6 is a side elevation view in cut away of the soft tissue and boneof FIG. 4 showing the anchor being actuated to lock the suture to theanchor and the anchor to the bone;

FIG. 7 is a side elevation view in cut away of the soft tissue and boneof FIG. 4 showing the anchor fully deployed;

FIG. 8 is a side elevation view in cut away of the soft tissue and boneof FIG. 4 showing the anchor in partial cut-away in its fully deployedposition;

FIG. 9 is a perspective view of a further embodiment of a suture anchoraccording to the present invention;

FIG. 10 is a perspective cut-away view of the suture anchor of FIG. 9.

DETAILED DESCRIPTION

FIG. 1 depicts a suture anchor 10 according to the present invention. Itcomprises in gross an inner body 12 having a distal end 14 and proximalend 16 and a cannulated outer body 18 having a distal end 20, proximalend 22 and a cannulation 24 therethrough. Towards the outer bodyproximal end 22 the cannulation 24 bears internal threads 26 whichdecrease in internal diameter at the proximal end 22. On its exteriorsurface 28 the outer body 18 bears barb shaped annular flanges 30 toassist in bone fixation.

The inner body 12 has an annular flange 32 at its distal end 14 with agroove 34 therethrough passing over the distal end 14. At its proximalend 16 the inner body 12 has exterior threads 36 which mate with theinner body threads 26. A pair of radially extending projections 38extend from the inner body 12 toward the outer body 18 at its distal end20. The tolerance between the projections 38 and the outer body 18should be close enough to prevent suture 39 from passing therebetween.

A tool receiving recess 40 on the inner body proximal end 16 mates witha driver head 42 (such as for instance a hex driver) on a distal end ofa driver 44. Just proximal thereof on the driver 44 are threads 46 whichmate with the threads 26 on the outer body 18. The threads 46 have areduced major diameter at a proximal portion 48 which in its startingconfiguration as shown in FIG. 1 sits adjacent the decreased internaldiameter of the outer body thread 26 at their proximal end 22. Thedriver 44 operates within a tube 50 having a distal end 52 abutting theouter body proximal end 22 with distally projecting tangs 53 extendinginto slots 54 in the outer body proximal end. This interface assists inmaintaining the position of the anchor 10 as it is employed, byresisting both rotation and proximal withdrawal thereof.

Turning also now to FIG. 2, two or more of the stress relief slots 54extend axially into the outer body 18 from its proximal end 22. Thisallows the proximal end to be made from somewhat brittle materials yetstill be able to expand outwardly radially to provide fixation. Both theinner body 12 and outer body 18 are preferably formed of a bioabsorbablematerial such as BIOCRYL RAPIDE available from DePuy Mitek, Inc. ofRaynham, Mass. BIOCRYL RAPIDE is a bioabsorbable polymer formed ofhomogenous blend of TriCalcium Phosphate (TCP) andPolylactic/polyglycolic Acid (PLGA). Other suitable materials includewithout limitation PEEK, PLA, titanium, stainless steel, metals,polymers and other biocompatible materials.

Turning also now to FIGS. 3 to 7, use of the suture anchor 10 will bedescribed. The anchor 10 is sterile and packaged in bacteria proofpackaging (not shown) pre-loaded onto the driver 44 and pre-loaded witha suture capture device 56 comprising an elongated filament 58 having asuture capture loop 60 at one end. One example is the CHIA PERCPASSERavailable from DePuy Mitek, Inc. of Raynham, Mass. The loop 60 in FIG. 3is shown adjacent the anchor 10 for ease of display but in practicesufficient length of the filament 58 would extend from the anchor 10 toallow suture 39 to be pulled out of a cannula (not shown) through whichthe procedure is being endoscopically performed.

The suture 39 would be loaded into the suture capture loop 60 exteriorof the patient and the cannula. A tab 62 may be placed on an oppositeend of the filament 58. (This is also shown adjacent the anchor 10 forease of display but would more conveniently be positioned outside of thecannula.) When the tab is pulled the loop 60 with the suture 39 capturedtherein is drawn down between the inner body 12 and outer body 18pulling the suture 39 with it. The path of the suture 39 after passingbetween the inner body 12 and outer body 18 goes through the groove 34to assist in sliding. Additional sutures can also be employed, such asadditional suture loops in the suture capture loop 60 or addition sutureloops each with their own suture capture device.

The anchor 10 with the suture 39 therein is now inserted into apre-drilled hole 64 in a bone 66 to which a piece of soft tissue 68 isto be attached as shown in FIG. 4. The anchor 10 is positioned in thehole 64 such that the suture passes into the anchor 10 at one of thestress relief slots 54. The suture 39 is shown looped through the softtissue 68 but other arrangements are possible such as extending fromanother anchor (not shown and typically of a different configurationthan anchor 10) which is positioned in the bone 66 below the soft tissue68 and up through the soft tissue 68 to the anchor 10, such as in a dualrow rotator cuff repair. Also, the path from the soft tissue 68 throughthe anchor 10 could be reversed.

Free ends 70 of the suture 39 are drawn through the anchor 10 toposition the soft tissue 68 and properly tension the suture 39 (see FIG.5). The tube 50 of the driver 44 holds the anchor 10 down and preventsrotation of the outer body 18 while the driver 44 is rotated to rotatethe inner body 18 (see FIG. 6). As the threads 46 of the driver 44 passthrough the reduced inner diameter proximal portion 22 of the outer body18 it causes it to expand outwardly radially to engage the bone 66 andreduces the stress on the inner body 18. Preferably, the relaxedcondition of the outer body 18 is slightly expanded radially and as itis inserted into the hole 64 it is compressed slightly inwardly; theexpansion by the threads 46 move it back to its relaxed configurationthus reducing internal stress. As the rotation continues the threads 36of the inner body move into the reduced inner diameter proximal portion22 to keep the outer body proximal end 22 radially expanded. Theprojections 38 on the inner body 12 cause the suture 39 to wrap aroundthe inner body 12. The suture 39 feeds in from the free ends 70, notfrom the soft tissue 68 so that the position of the soft tissue 68 andthe tension on the suture 39 between the anchor 10 and the soft tissue68 remains substantially unchanged as the inner body 12 is rotated.After sufficient rotation the driver 44 is disengaged from the anchor 10and removed leaving the suture 39 locked to the anchor 10 by virtue ofits being wrapped around the inner body 12 and the outer body proximalend 22 is expanded outwardly into the bone 66 to lock the anchor 10thereto (see FIGS. 7 and 8). Tests have shown three to five turnsproviding good locking of the suture 39.

FIGS. 9 and 10 illustrate a further preferred embodiment of theinvention which is essentially similar to that depicted in FIGS. 1 and2. Like parts are denoted with like numerals with the addition of aprime symbol (′). It comprises a suture anchor 10′ having an inner body12′ and cannulated outer body 18′ having a short internal thread 24′.The inner body 12′ has an annular flange 32′ at its distal end 14′ witha groove 34′. It also carries radially extending projections 38′. FIG. 9especially more clearly illustrates how a driver receiving tube 50′abuts a proximal end 22′ of the outer body 18′ with distally projectingtangs 53′ extending into stress relief slots 54′. A loop of suture 39′has free ends which pass into the outer body 18′ from its proximal end22′, preferably through one of the stress relief slots 54′, passes downbetween the inner body 12′ and outer body 18′ and between theprojections 38′, out of the outer body 18′ through its distal end 20′,through the groove 34′ on the inner body 12′ at its distal end 14′ andthen back into the outer body 18′ between it and the inner body 12′ andalso again between the projections 38″ and finally exit through theopposing stress relief slot 54′. This embodiment is used similarly tothe previous one. However, the groove 34′ assists in wrapping the suture39′ around the inner body 12′ and one could even dispense with theprojections 38′ due to the wrapping action provided by the groove 34′.

Various modifications and alterations of this invention will be apparentto those skilled in the art without departing from the scope and spiritof this invention. It should be understood that the invention is notlimited to the embodiments disclosed herein, and that the claims shouldbe interpreted as broadly as the prior art allows.

1. A suture anchor comprising: an outer body having a distal end aproximal end and an axial bore therethrough; an inner body receivablewithin the outer body; a suture limb captured between the inner body andthe outer body by being wrapped around the inner body, a first portionof the suture limb passing out of the outer body whereby it may beconnected to a tissue and a second portion of the suture limb passingout of the outer body whereby to allow a tension to be applied to thesuture limb by a user; the inner body having a distal end and a proximalend and wherein the inner body proximal end has outer threads which matewith inner threads on the proximal end of the outer body; and the outerbody having a first configuration in which at least a portion thereof isradially contracted inwardly and a second configuration in which theportion is radially expanded outwardly, and wherein when the outerthreads on the inner body are engaged into the outer body inner threadsit holds the portion in the second configuration.
 2. A suture anchoraccording to claim 1 wherein the inner body and the outer body areformed of a bioabsorbable material.
 3. A suture anchor according toclaim 2 wherein the inner body and outer body are formed of PLGA. 4.(canceled)
 5. A suture anchor according to claim 1 configured such thatas the inner body is moved toward the proximal end of the outer body theproximal end of the outer body expands outwardly radially.
 6. A sutureanchor according to claim 1 wherein the suture limb is wrapped aroundthe inner body at least two times.
 7. A suture anchor according to claim6 wherein the suture limb is wrapped around the inner body at least fivetimes.
 8. A suture anchor according to claim 6 wherein the inner bodycomprises at least one tab extending outwardly radially whereby toeffect wrapping of the suture about the inner body upon rotation of theinner body.
 9. (canceled)
 10. A suture anchor according to claim 1 andfurther comprising an inserter having a distal end which mates with theproximal end of the inner body and which has outer inserter threadsengageable with the inner threads on the outer body. 11-12. (canceled)13. A suture anchor according to claim 121 wherein a naturally relaxedposition of the portion is in the second configuration.
 14. A sutureanchor according to claim 1 wherein the suture limb passes into a spaceformed between the inner body and the outer body at their proximal ends,passes out of the space at their distal ends and then passes proximallyalong an outer surface of the outer body.
 15. A suture anchor accordingto claim 1 wherein the outer body has at its proximal end at least oneaxially extending slit therein whereby to relieve stresses upon radiallyoutward expansion of the outer body proximal end.
 16. A suture anchoraccording to claim 1 and further comprising at least one more suturelimb captured between the inner body and the outer body.
 17. A sutureanchor according to claim 1 and further comprising at least three moresuture limbs captured between the inner body and the outer body. 18-23.(canceled)
 24. (canceled)
 25. A suture anchor according to claim whereinrotation of the inner body simultaneously winds the suture limb aroundthe inner body and expands the outer body into its second configuration.